Linkage analysis using maximum-likelihood estimation is a powerful tool for locating genes. As available data sets have grown, the computation required for analysis has grown exponentially and become a significant impediment. Others have previously shown that parallel computation is applicable to linkage analysis and can yield order-of-magnitude improvements in speed. In this paper, we demonstrate that algorithmic modifications can also yield order-of-magnitude improvements, and sometimes much more. Using the software package LINKAGE, we describe a variety of algorithmic improvements that we have implemented, demonstrating both how these techniques are applied and their power. Experiments show that these improvements speed up the programs by an order of magnitude, on problems of moderate and large size. All improvements were made only in the combinatorial part of the code, without restoring to parallel computers. These improvements synthesize biological principles with computer science techniques, to effectively restructure the time-consuming computations in genetic linkage analysis.

Faster sequential genetic linkage computations.

In spite of recent advances in identifying genes causing monogenic human disease, very little is known about the genes involved in polygenic disease. Three families were identified with mutations in the unlinked photoreceptor-specific genes ROM1 and peripherin/RDS, in which only double heterozygotes develop retinitis pigmentosa (RP). These findings indicate that the allelic and nonallelic heterogeneity known to be a feature of monogenic RP is complicated further by interactions between unlinked mutations causing digenic RP. Recognition of the inheritance pattern exemplified by these three families might facilitate the identification of other examples of digenic inheritance in human disease.

https://science.sciencemag.org/content/sci/264/5165/1604.full.pdf

Digenic retinitis pigmentosa due to mutations at the unlinked peripherin/RDS and ROM1 loci

We describe four improvements we have implemented in a version of the genetic linkage analysis programs in the LINKAGE package: subdivision of recombination classes, better handling of loops, better c

Lorraine H. Friedman

Papers

Linkage mapping of autosomal dominant retinitis pigmentosa (RP1) to the pericentric region of human chromosome 8